<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <link rel="stylesheet" href="./index.css">
</head>

<body>
    <div class="wrap">
        <div class="title">学生系统</div>
        <div id="form">
            <p>姓名<input id="username" type="text" value="张三123" /></p>
            <p>年龄<input id="age" type="text" value="21" /></p>
            <p>性别
                <select id="gender">
                    <option>男</option>
                    <option>女</option>
                    <option>你猜</option>
                </select>
            </p>
            <p>
                <input type="button" value="添加" id="addBtn" />
                <input type="button" value="排序" id="sortBtn" />
            </p>
        </div>
        <table id="table">
            <thead>
                <tr>
                    <th>姓名</th>
                    <th>年龄</th>
                    <th>性别</th>
                    <th>操作</th>
                </tr>
            </thead>
            <tbody>

            </tbody>
        </table>
    </div>

    <script>
        // 获取 元素
        var usernameEle = document.querySelector("#username");
        var ageEle = document.querySelector("#age");
        var genderEle = document.querySelector("#gender");
        var addBtn = document.querySelector("#addBtn");

        var tbodyEle = document.querySelector("tbody");

        // 点击添加按钮的时候 ，添加用户信息
        addBtn.onclick = function(){
            var username = usernameEle.value;
            var gender = genderEle.value;
            var age = ageEle.value;
            // console.log(username,gender,age);
            // 需要根据添加的的内容 组装成tr标签 然后添加到tbody里；
            // 创建一个tr标签 
            var trEle = document.createElement("tr");
            trEle.innerHTML = "<td>"+username+"</td>"+
                              "<td>"+age+"</td>"+
                              "<td>"+gender+"</td>"+
                              "<td>删除</td>";
            tbodyEle.appendChild(trEle)  ; 
        }

    </script>
</body>

</html>